In a statement issued here the hospital said the 94-year-old leader was admitted into ICU at 1.30 a.m.

"His blood pressure has been stabilised since with medical management. He continues to be monitored and treated by a panel of expert doctors," Kauvery Hospital's Executive Director Aravindan Selvaraj said.

The five time former Chief Minister of Tamil Nadu has been suffering from urinary tract infection and age-related ailments and was earlier under treatment at his home.

A large number of DMK cadres have gathered outside the hospital and a huge contingent of policemen was deployed for security.

Speaking to reporters here DMK leader A. Raja urged the party cadres to remain calm and said: "Karunanidhi's blood pressure is now normal and there is nothing to worry".

A team of doctors had reached Karunanidhi's home about midnight and reviewed his condition. They then decided to shift him to the hospital after discussions with the family members.

On Friday DMK leader and Karunanidhi's son M.K. Stalin said there "is good improvement in the health condition of Kalaignar" as the infection had come down a lot.

On Thursday, in a statement issued by the Kauvery Hospital, the Executive Director said the DMK patriarch was under treated for fever due to urinary tract infection with intravenous antibiotics and fluids.

"He is being monitored and treated round the clock by a team of medical and nursing professionals, who are providing hospital-level care at his home," Selvaraj said.

Earlier Karunanidhi was admitted to the same hospital for change of the tracheostomy tube.